The main character, Dr. Cal Lightman (played by Tim Roth), detects deception by observing body language and microexpressions through the Facial Action Coding System (NLP visual accessing cues are also used), using this talent to assist clients (such as law enforcement). The character is based on Paul Ekman, notable psychologist and expert on body language and facial expressions. Dr. Ekman and his colleague, Dr. Maureen O'Sullivan, identified "naturals" in what is known as The Wizards Project, which identified 50 people with the ability to spot deception after testing 20,000 people from all walks of life. In real life, they call these "naturals" Truth Wizards, or wizards of deception detection.